Pedro M. Ramos

Bio: Pedro M. Ramos is an academic researcher from Instituto Superior Técnico. The author has contributed to research in topics: Signal processing & Signal. The author has an hindex of 22, co-authored 134 publications receiving 1977 citations. Previous affiliations of Pedro M. Ramos include University of Lisbon & University of Évora.

Tactile sensors for robotic applications

Abstract: In this paper, the authors look at the domain of tactile sensing in the context of Robotics. After a short introduction to support the interest of providing robots with touch, the basic aspects related with tactile sensors, including transduction techniques are revisited. The brief analysis of the state-of-the-art of tactile sensing techniques that follows provides indicators to conclude on the future of tactile sensing in the context of robotic applications.

PQ Monitoring System for Real-Time Detection and Classification of Disturbances in a Single-Phase Power System

Abstract: This paper presents a system for detection and classification of power quality (PQ) voltage disturbances. The proposed system applies the following methods to detect and classify PQ disturbances: digital filtering and mathematical morphology are used to detect and classify transients and waveform distortions, whereas for short- and long-duration disturbances (such as sags, swells, and interruptions), the analysis of the root-mean-square (RMS) value of the voltage is employed. The proposed combined approach identifies the type of disturbance and its parameters such as time localization, duration, and magnitude. The proposed system is suitable for real-time monitoring of the power system and implementation on a digital signal processor (DSP).

Advanced technique for non-destructive testing of friction stir welding of metals

Abstract: In this paper a new non-destructive testing (NDT) system focusing on micro size superficial defects in metallic joints is presented. The innovative system is composed by a new type of eddy currents probe, electronic devices for signal generation, conditioning and conversion, automated mechanized scanning and analysis software. The key original aspect of this system is the new type of eddy currents probe. This new probe provides enhanced lift-off immunity and improved sensitivity for micro size imperfections. The probe concept was studied using a Finite Element Method (FEM) tool and experimental verified using a standard defect. The testing results on some friction stir welding (FSW) specimens clearly show that the system is able to detect superficial defects less than 60 μm deep, which significantly increases the actual state of the art in NDT reliability for micro imperfections detection. The system can be applied to a broad range of industries which include manufacturing, maintenance and engineering companies.

A new sine-fitting algorithm for accurate amplitude and phase measurements in two channel acquisition systems

Abstract: Sine-fitting algorithms are very accurate methods to estimate the parameters (amplitude, phase, frequency and DC component) of a digitized sinusoidal signal. In this paper, the standardized algorithms are improved, producing a new algorithm to estimate the sinewave parameters of two acquired sine signals sharing a common frequency. This new algorithm can be used for example in impedance measurements or in the accurate frequency characterization of linear systems by measuring its input and output and varying the input signal frequency.

New Spectrum Leakage Correction Algorithm for Frequency Estimation of Power System Signals

Abstract: A new algorithm for the estimation of the frequency of single-tone signals is presented in this paper. The algorithm works in the frequency domain and is based on best fitting a theoretical spectrum of a single-tone signal that is windowed using a rectangular window on the spectrum of the sampled signal. Using this iterative process, the algorithm compensates the spectrum leakage caused by incoherent sampling and a finite number of samples. Due to leakage compensation, the algorithm provides accurate estimates of the signal's frequency, amplitude, and phase. The influence of noise and harmonic and interharmonic distortions on the proposed algorithm was investigated and is reported here. The algorithm's performance was compared with several other frequency-estimation algorithms (mostly those working in the frequency domain). Since the algorithm is intended for power quality measurements (although it is not limited to this application), it was also tested on signals measured in a single-phase power system.

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

Recent advances in wearable tactile sensors: Materials, sensing mechanisms, and device performance

Abstract: Tactile sensors, most commonly referred as strain and pressure sensors, can collect mechanical property data of the human body and local environment, to provide valuable insights into the human health status or artificial intelligence systems. The introduction of a high level of wearability (bendability and stretchability) to tactile sensors can dramatically enhance their interfaces with the contact objects, providing chronically reliable functions. Therefore, the developed wearable tactile sensors are capable of conformably covering arbitrary curved surface over their stiff counterparts without incurring damage, emerging as a promising development direction toward the Internet of Things (IoT) applications. Fundamental parameters of the wearable tactile sensors such as sensitivity and stretchability have experienced unprecedented advancement, owing to the progress of device fabrication techniques and material structural engineering. Moreover, novel smart materials and mechanically durable sensor design concepts endow these sensors with multi-functionality integration (e.g., simultaneous force, temperature and humidity detection, simultaneous pressure and strain discrimination) and stirring properties (e.g., biocompatibility, biodegradability, self-healing, self-powering and visualization), further broadening the application scope of current wearable tactile sensors. Besides, it is desirable that a tactile sensor is compatible with a printing process that presents a new era of feasible wearable technology due to its large-area and high-throughput production capability. In addition to the development of sensors, packaging, and integration of the rest of the tactile device system (data memory, signal conversion, power supply, wireless transmission, feedback actuator, etc.) to build a wearable platform also emerge as major research frontiers in recent years. This review attempts to summarize the current state-of-the-art wearable tactile sensors concerning basic concepts, functional materials, sensing mechanism, promising applications, performance optimization strategies, multifunctional sensing, and system integration. Finally, the discussion will be presented regarding potential challenges, pathways, and opportunities.

Toward Perceptive Soft Robots: Progress and Challenges

Abstract: In the past few years, soft robotics has rapidly become an emerging research topic, opening new possibilities for addressing real-world tasks Perception can enable robots to effectively explore the unknown world, and interact safely with humans and the environment Among all extero- and proprioception modalities, the detection of mechanical cues is vital, as with living beings A variety of soft sensing technologies are available today, but there is still a gap to effectively utilize them in soft robots for practical applications Here, the developments in soft robots with mechanical sensing are summarized to provide a comprehensive understanding of the state of the art in this field Promising sensing technologies for mechanically perceptive soft robots are described, categorized, and their pros and cons are discussed Strategies for designing soft sensors and criteria to evaluate their performance are outlined from the perspective of soft robotic applications Challenges and trends in developing multimodal sensors, stretchable conductive materials and electronic interfaces, modeling techniques, and data interpretation for soft robotic sensing are highlighted The knowledge gap and promising solutions toward perceptive soft robots are discussed and analyzed to provide a perspective in this field

A review of numerical analysis of friction stir welding

Abstract: Friction stir welding is a relatively new solid-state joining technique which is widely adopted in different industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a highly complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints and their three dimensional nature make it difficult to develop an overall system of governing equations for theoretical analyzing the behavior of the friction stir welded joints. The experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used since the 2000s. This paper reviews the latest developments in the numerical analysis of friction stir welding processes, microstructures of friction stir welded joints and the properties of friction stir welded structures. Some important numerical issues such as materials flow modeling, meshing procedure and failure criteria are discussed. Numerical analysis of friction stir welding will allow many different welding processes to be simulated in order to understand the effects of changes in different system parameters before physical testing, which would be time-consuming or prohibitively expensive in practice. The main methods used in numerical analysis of friction stir welding are discussed and illustrated with brief case studies. In addition, several important key problems and issues remain to be addressed about the numerical analysis of friction stir welding and opportunities for further research are identified.

Grasp quality measures: review and performance

Abstract: The correct grasp of objects is a key aspect for the right fulfillment of a given task. Obtaining a good grasp requires algorithms to automatically determine proper contact points on the object as well as proper hand configurations, especially when dexterous manipulation is desired, and the quantification of a good grasp requires the definition of suitable grasp quality measures. This article reviews the quality measures proposed in the literature to evaluate grasp quality. The quality measures are classified into two groups according to the main aspect they evaluate: location of contact points on the object and hand configuration. The approaches that combine different measures from the two previous groups to obtain a global quality measure are also reviewed, as well as some measures related to human hand studies and grasp performance. Several examples are presented to illustrate and compare the performance of the reviewed measures.